accessible: fix if (!foo != const) construct

Fixes a Clang warning.

Change-Id: I114cf0f84ef9a4fe4ae814cedca883945d76e86c
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
tst_QTextLayout: fix unhandled enum value in switch warning

Change-Id: I006286487a409d492fe398a2fed5dd854f758f9f
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>
xcb: QWindow never uses XCB_GRAVITY_CENTER

Center gravity doesn't mean center the window, it only affects the
method of converting between internal window bounds and decorated bounds.
So wanting to have each dialog centered w.r.t. its transient parent
is not a reason for using center gravity.  Instead it caused the
bug that when you resize a QMessageBox by clicking the Show Details
button, it jumps downwards on the screen.

Task-number: QTBUG-32473
Change-Id: I3fabf3caa1e4d10fd4f7508e297f73efe5cc51b6
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>